Pressure Switch Error but only between Midnight and 6 a.m.

I have an American Standard, Model: YCC024F1L0BH.
Yesterday morning I woke up at 5:00 a.m. and the house was cold, the heater was off and wouldn't turn on, and the LED on the unit was flashing 3 times (Pressure Switch Error). Turned it off and on a couple of times and about an hour later (6:00 a.m.) it just kicked on and worked fine all day.

That night about 11:30 p.m. it went off again, wouldn't turn back on, and the LED was flashing 3 times again. Cycled it off and on a few times and nothing happened so left it on and went to bed. Got up at 6:00 a.m. and the heater was on and working fine - and has worked fine all day.

What could cause pressure switch error's only between midnight and 6:00 a.m.?

After the first time it went off I: Replaced the filter, checked the registers to make sure they were open and not blocked, checked around the unit for anything blocking the air flow, and made sure the thermostat was on hold and not a program.

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Is that a mid or high efficiency unit. Does it have plastic pipes venting it to the outside? If so check them for snow/obstructions. Where the tube from the pressure switch attaches to the collector box/ventor fan or wherever on yours remove it and poke the port thru with a nail as they get smutz in there.

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I had something very similar happen to mine. As the poster above said, check both ends of where that tube connects to. I had stuff plugging mine, and it happened at both ends of the tube on different times. I had to disconnect the pressure switch and suck on it a couple times to clear the crud too.

Is that a mid or high efficiency unit. Does it have plastic pipes venting it to the outside? If so check them for snow/obstructions. Where the tube from the pressure switch attaches to the collector box/ventor fan or wherever on yours remove it and poke the port thru with a nail as they get smutz in there.

It is an outside unit so no plastic pipes venting to the outside. I'm not sure where the pressure switch is located inside the unit. There are panels all the way around and I don't know what the pressure switch looks like.

Google: furnace pressure switch and then hit Images for hordes of em. also google that term and there are u tube vids.

Finally found the pressure switch. Checked the tube and it was clear. Found a cheap pressure switch so think I'll change that out and see what that does. It will either fix the problem or eliminate a possible cause. Thanks for your input - will post after I change it out.

The pressure switch is a safety device. Replace it only with one that is perfectly matched to the specifications of the original. Not doing this can cause a potentially dangerous situation causing further issues or damage to the unit that will be only cost effective to replace the entire unit.

Finally found the pressure switch. Checked the tube and it was clear. Found a cheap pressure switch so think I'll change that out and see what that does. It will either fix the problem or eliminate a possible cause. Thanks for your input - will post after I change it out.

Is it the right pressure switch though? As in the same pressure setting.

Did you get the exact same rating of switch in inches water colum ie "WC. If not you now have a very dangerous situation. We are concerned when you mentioned "cheap" switch as they are NOT all the same. If it has no ratings then you need to get it from the manufacturer.

Last night it quit around 10:30 p.m. but was running when I got up this morning at 6:00 a.m. and ran fine until 11:00 p.m. tonight then quit again. Still getting the 3 flashes (Pressure Switch Error). While outside I heard the switch click and it tried to start but nothing after that.

What can fail and give a pressure switch error but not be the pressure switch?

need to get the "WC rating of the switch and a manometer and check if there is enough suction at the switch. if it is borderline then a change in temp can change that amount and trip it. usually you should have an extra .5 " above the rating if the unit is working properly. or call a Pro and have him check the entire unit properly.